Vessel stern



D. w TAYLOR VESSEL STERN April 12, 1932.

Filed July 26, 1929 2 Sheets-Shee t 1 Fig 1 INVENTOR. 90M a/"J ATTORNEY D, W. TAYLOR VESSEL STERN April 12, 1932.

2 Sheets-Sheet 2 Filed July 26, 1929 INVENTOR. ada t-601w Z01" ATTORNEY Patented Apr. 12, 1932' UN-ITED' srAT Es DAVID w. TAYLOR-o1. WASHINGTON, DISTRIGTOF COLUMBIA V'ESSEL STERN 7 Application .filed July 26, 1929. Serial No. 381,356.

This invention comprises improvements in the construction of the stern of vessels in connection with propellers not on the centre line of vessel, i. e., side propellers.

5 It is well known that in the operation 0 the screw propeller of a ship, there are mutual reactions between the propeller and the v hull to which it is attached.

In general, it can be said that in regions 7 10 where a propeller is drawing the water away from the vessel, there is a reduction of pressure, whereas there is an increase of pressure with a forward component on the vessel where thewater is driven toward the vessel.

In particular the propeller, in addition to developing thrust which is communicated through its shaft to the thrust block,'exerts a suction upon the part of the hull, adjacent to it, commonly spoken of as thrust deduction, because it neutralizes a part of the thrust on the thrust block.

As the water of the race leaves thepropeller it has a certain amount of rotary velocity, the rotary momentum of the race being directly proportional to the torque of the propeller.

There have been many propositions to install fittings which would utilize this'rotary component of the propeller race and convert 39 the velocity into forward pressure upon the fitting installed.

All of these propositions, however, have consisted of devices which understake to influence the entire race of the propeller, i. e., both that portion of the race above the centre of thepropeller and that portion of the race below the centre of propeller. Such devices usually have guide blades to receive the water edgewise, the inclination of the blades varying with the direction of rotation of the propeller, whether out-turning or in turning, and sometimes varying with radial distance from the axis of the'propeller, all designed to obtain a favorable reaction from the water of the race directly upon the device.

My invention, however, is to utilize this rotary velocity not directly, but indirectly, and in this respect it differs from known de" vices so as to be effective with side propellers.

Referring to the drawings in which like parts are similarly designated- Figure 1 is a stern view of a side propeller with the curvature of the hull shown by various sections. v

Fig. 2 is a like view showing my invention as applied thereto as a single plate.

Fig. 3 is a side view of Figure 2. Figs. at and 5 show stern views of practical constructions.

Fig. (Sis a side view of Figure 4, and

Fig. 7 is a side view with'a'rudder attached.

Figure 1 indicates a stern View and a number of sections, ab' to a-e, of the hull in the vicinity of the side propeller which turns outward as indicated by the arrow. This propeller eXerts suction forward of it,'which suction is communicated to the hull section's forward, such as a0adac, and produces the thrust deduction. Byinstalling behind the upper part of the propeller a fixed appendage, as indicated in end elevation by fg in Figure 2, and fgh7c in side elevation in Figure 3, the rotation of the upper part of the race is stopped or blocked. This results in an increase of pressure between f-Eg and the hull. This increase of pressure acting upon the hull'nullifies or neutralizes wholly or in largepart the normal thrust deduction.

It will be observed that this appendage extends little below the centre of the propeller. This is for the reason that the rotation of the lower part of the propeller race which extends from the propeller rearward and in which the. rotating water is moving toward the hull, is not prejudicial but beneficial. It

is only the rotation in the upper part of the race wherethe water is'moving away from the hull that'l wish to check. However, it is advisable to extend the appendage somewhat below the centre of the propeller to an extent not over one-sixth of the diameter of the race or propeller, as clearly indicated in- Figure 3. This is for the reason that for a moderate distance below the centre of the propeller race or axis of the propeller its rotary velocity is small and the larger or deeper appendage converts into pressure more efliciently the rotary velocity of the upper part of the race.

The ideal installation is a single plate, Figs. 2 and 3, so arranged that if the propeller is not working it is edgewise to the normal flow of the water and hence produces minimum interferences with the normal stream-lines.

However, it is impossible for structural reasons to make the appendage a single plate, but one of a construction and of such section as to present a minimum resistance to the flow of the water, i. e., having the stream-line surfaces as shown by 0-p,.18 and o-p v in Figures 1-5 and 6 respectively, can be readily applied to the structure of the vessel. Furthermore, it is possible and usually desirable to have only part of the appendage fixed and to have the rest utilized as a rudder, as illustrated in Figure 7, normally in a middle position but producing a powerful steering effect owing to its situation in the wash from the propeller.

The appendage 0"p-o, Fig. 7, depending vertlcally from the hull has a rear edge portion 0p to which is fitted in customary manner arudder g.

It will be observed that the drawings show appendages blocking rotation over the upper part of the race corresponding to outturning propellers. For in-turning propelhere an appendage blocking rotation over the lower part of the race would exemplify my idea and be beneficial. Obviously, for structural reasons it would be much more difiicult to apply, so that in practice when my invention is made use of, out-turning side propellers would usually be used.

It will be observed further, that my appendages are as nearly as practicable thin planes with no appreciable resulting forward component, resulting from the pressures upon them caused by blocking the rotation of the water in the race. It is by thefavorable reactions of these pressures communicated through the water to the after part of the vessels hull, which pressures will tend to push the hull forward, that I gain an increase of propulsive efiiciency.

\Vhilemy appendage is preferably vertical or nearly so, this is not essential, and a moderate departure from the vertical, even to the extent of making it normal to the surface of the hull, if the latter is fairly fiat in section is allowable, as shown in Fig. 5.

I The essential feature, in this regard, is that the surface of the appendage shall be substantially a fore and aft plane whatever its inclination to the vertical, extending across only that portion of the race rotating away from the hull with structures such as shown.

I claim 1. An improved means for propelling multiple screw vessels, comprising the combination with the hull of the vessel, and a side screw propeller; a fixed appendage immediately behind the propeller and a rudder aft of said appendage, but neither extending materially beyond the centre of the propeller race, the rudder and fixed appendage combining to convert the detrimental rotational momentum in a portion of the propeller race into forces useful for propelling the vessel.

2. An improved means for propelling multiple screw vessels, comprising the combination with the hull of the vessel, and a side screw propeller; of a perpendicular appendage on the hull immediately behind the pro aeller, but not extending to the propeller tips, to block the rotational movement in the portion of the propeller race above the centre of the propeller and thereby convert the rotational momentum of the blocked portion of the race into forces useful for propelling the vessel.

3. An improved means for propelling multiple screw vessels, comprising the combination with the hull of the vessel, and a side screw propeller; of a vertical appendage depending from the hull immediately behind the propeller, said appendage having a vertical rear edge and a stream-line surface, a rudder articulated to said rear edge and forming a rearward extension of said appendage and both rudder and appendage extending downward to block the rotational outward movement of the propeller race and thereby convert the outward rotational momentum of the blocked portion of the ralce into forces useful in propelling the vesse 4. An improved means for propelling multiple screw vessels, comprising the combination with the hull of the vessel, and a side screw propeller; of an approximately vertical appendage supported from the hull, located immediately behind the propeller and blocking a portion of the rotational movement of the propeller race, said appendage extending past the centre of the race and propeller not to exceed one-sixth their diameter.

In testimony that I claim the foregoing as my inventinon, I have signed my name hereto.

DAVID V. TAYLOR. 

